1. Field of the Invention
The present invention relates to hydrocarbon production and, more specifically, to a process to make synthetic liquid hydrocarbons from carbon dioxide, obtained from seawater or air, and hydrogen from water without the use of fossil fuels in any step of the process. Description of the Related Art
2. Description of Prior Art
The United States Navy uses over a billion gallons of liquid hydrocarbon fuel each year. The fuel is procured from petroleum refineries and suppliers around the world and is transported to its final location of use. This can involve fuel shipments over thousands of miles and many weeks of transport. Moreover, implementing fuel cells on ships requires a hydrogen carrier such as liquid hydrocarbon fuels that are extremely low in sulfur content since this contaminant will poison the fuel cell fuel reformer.
Although the idea for developing synthetic liquid hydrocarbon fuels has been discussed for at least the last 30 years, there has not been an apparent need to produce them because of the availability, ease of processing, and high-energy conversion efficiency of fossil fuels. However, the fossil fuel market is changing. One reason for this change is the ongoing political instability in oil producing regions. Another reason is the increasing worldwide energy demand.
There are several disadvantages to using fossil fuels. First, fossil fuels are a limited resource that cannot be regenerated. Additionally, hydrocarbon fuels made from fossil fuels may contain highly undesirable sulfur, nitrogen, and aromatic compounds. When these fuels are burned, sulfur, nitrogen, and particulates are released into the air, which leads to the formation of acid rain and smog.
There are several well-established processes for direct hydrogenation of gases such as CO or CO2 to produce hydrocarbon fuels. One of the most successful was developed in Germany in the 1920s by Franz Fischer and Hans Tropsch. In 1938, early German plants produced 591,000 metric tons per year, approximately 5×106 barrels per year or approximately 2×108 gallons/year, of oil and gasoline using the Fischer-Tropsch process, which reacts carbon monoxide and hydrogen with a catalyst to produce liquid hydrocarbons and water. The problem with these methods is that they use fossil fuels to produce the CO, CO2, and H2 used.
Additionally, well-known methods have been developed to produce methanol from carbon dioxide and hydrogen. One successful process is the Lurgi process. Methanol can also be used as a feedstock to produce traditional automotive gasoline. The problem with these methods is that the flash point of methanol is 11° C. and the flash point of gasoline is well below 0° C. Therefore, these methods cannot be used at sea, since the International Maritime Organization and the U.S. Navy require a minimum 60° C. flash point for all bulk flammable liquids on ships.